J.P.
My son did this as well, not to such a degree, but he had more accidents at home than at daycare. What I finally did was that we set a timer for 15 minutes (at first). Every time it went off, we actually went to the bathroom and he sat on the potty. We went through the whole process, whether he went or not. When we came back, fifteen more minutes. Once that worked well enough, we increased the time. That worked well for pee, but he would not poop until we put him in a pull-up/diaper to go to bed. The only way we were able to stop THAT was that we got him a toy he really wanted, and every time he pooped in the potty, he could play with the toy for one hour. (We had to adjust that to you can play with it that day/next day because he would try to separate his trips out to get the max amt of hours possible. Kids are so creative when they want something.) Anyway, if he pooped in his underwear, they went in the trash. A friend made her son clean his underwear, and that worked for them, but my son loves to play with water and soap, so I thought it might backfire for us!